The present invention relates to an ultrasonic operation apparatus including a handpiece adapted to, for example, incise or emulsify a living tissue or destroy a stone in the living body.
In recent years, ultrasonic operation apparatuses have been used in more extensive fields beyond previously utilized fields, such as surgery on the liver having many blood vessels and brain surgery involving many nerve tissues. Heretofore, different kinds of ultrasonic operation apparatuses are proposed in accordance with their uses.
FIG. 8 shows an arrangement of an ordinary ultrasonic operation apparatus. In FIG. 8, reference numeral 1 shows an apparatus body and reference number 2 shows a handpiece. An ultrasonic oscillation element 3 is incorporated in the handpiece 2. A probe 4 is connected to the ultrasonic oscillation element 3. The ultrasonic oscillation element 3 is of such a type as to oscillate with a resonant frequency f1. In this case, the apparatus body 1 includes an oscillator 5 adapted to oscillate with a frequency corresponding to the resonant frequency f1 and a power amplifier 6 adapted to amplify a frequency signal from the oscillator 5. That is, the oscillator 5 in the apparatus body 1 generates a drive signal corresponding to the resonant frequency f1 of the handpiece 2 and is so designed as to generate only a resonant frequency corresponding to the specific handpiece 2 of the apparatus.
FIG. 9 shows another conventional form of ultrasonic operation apparatus. This apparatus includes two kinds of handpieces 2a and 2b having, for example, 23 kHz and 35 kHz, respectively, the handpiece 2a oscillating with a resonant frequency f1 and the handpiece 2b oscillating with a resonant frequency f2. An apparatus body 1 includes two oscillators 5a and 5b adapted to generate drive signals corresponding to resonant frequencies f1 and f2 of the handpieces 2a and 2b and a switching means 7 adapted to switch one of these drive signals.
In this connection, it is to be noted that the oscillator 5 in the conventional ultrasonic operation apparatus is so designed as to generate only a resonant frequency corresponding to the specific handpiece 2 of the apparatus. For this reason, it is, therefore, necessary to prepare a specific apparatus body 1 corresponding to the handpiece 2 used.
If different variants as the handpiece 2 are provided in accordance with the uses to which they are put, it is necessary to prepare many more specific apparatus bodies in accordance with the these variant handpieces 2. In this respect, the conventional system has proved to be very uneconomical.
Although any one of the two kinds of handpieces 2a, 2b was able to be driven in the apparatus of such a type as to have two oscillators 5a and 5b for generating drive signals corresponding to resonant frequencies f1 and f2 of the handpieces 2a and 2b, it was not possible to use the apparatus body 1 for other types of handpieces.
Further, even in the case where an entirely new handpiece was developed, it was not possible to use the existing apparatus body on many occasions. If the kinds of handpieces are to be increased, it is necessary to improve the apparatus body and add a corresponding oscillator for generating a given frequency to the apparatus body. Such an improvement consumes more time and costs more money In addition, such an improvement is not very efficient.
If the oscillation frequency is low, it is possible to provide a larger-sized handpiece While, on the other hand, if a high oscillation frequency is used, it is possible to obtain a smaller-sized handpiece. That is, for a shorter wavelength it is possible to provide a smaller-sized handpiece and it is desirable to selectively use various kinds of handpieces depending upon the situation under which a surgery or operation is performed. As set out above, however, it is required that, in actual practice, a different apparatus including a power source unit be prepared, as a principle, for each handpiece and it is difficult to adopt this system in reality.
An associated conventional control circuit is comprised of an analog circuit. The analog circuit needs to be designed, taking into consideration a variation in manufacturing cost and in parameters caused by a variation in the environment. With recent advances in the digital techniques, digital processing has been adopted on various associated apparatuses. Even in this kind of ultrasonic operation apparatus, the ultrasonic oscillation element has the characteristic of possessing a mechanical resonance frequency and it has various frequencies in accordance with the designing of the probe and ultrasonic oscillation element.
In the case where, in order to prepare handpieces adaptable to various operations or surgeries, their mechanical dimension is varied, the resonant frequency varies in a delicate range. Even where designing is effected in such a delicate frequency range, if an associated circuit is constructed in the conventional analog type control system, then there are cases where it is difficult to effect control on the setting of the delicate frequency due to a variation in the environment, etc., at the driving of the handpiece involving a variation in a delicate frequency range. Even if there are more types of resonant frequencies involved, it has been difficult to readily handle the problem above by the associated apparatus.